diff options
Diffstat (limited to 'drivers/rtc/rtc-m41t94.c')
| -rw-r--r-- | drivers/rtc/rtc-m41t94.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-m41t94.c b/drivers/rtc/rtc-m41t94.c new file mode 100644 index 000000000..6803b0273 --- /dev/null +++ b/drivers/rtc/rtc-m41t94.c @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for ST M41T94 SPI RTC + * + * Copyright (C) 2008 Kim B. Heino + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/rtc.h> +#include <linux/spi/spi.h> +#include <linux/bcd.h> + +#define M41T94_REG_SECONDS 0x01 +#define M41T94_REG_MINUTES 0x02 +#define M41T94_REG_HOURS 0x03 +#define M41T94_REG_WDAY 0x04 +#define M41T94_REG_DAY 0x05 +#define M41T94_REG_MONTH 0x06 +#define M41T94_REG_YEAR 0x07 +#define M41T94_REG_HT 0x0c + +#define M41T94_BIT_HALT 0x40 +#define M41T94_BIT_STOP 0x80 +#define M41T94_BIT_CB 0x40 +#define M41T94_BIT_CEB 0x80 + +static int m41t94_set_time(struct device *dev, struct rtc_time *tm) +{ + struct spi_device *spi = to_spi_device(dev); + u8 buf[8]; /* write cmd + 7 registers */ + + dev_dbg(dev, "%s secs=%d, mins=%d, " + "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", + "write", tm->tm_sec, tm->tm_min, + tm->tm_hour, tm->tm_mday, + tm->tm_mon, tm->tm_year, tm->tm_wday); + + buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */ + buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec); + buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min); + buf[M41T94_REG_HOURS] = bin2bcd(tm->tm_hour); + buf[M41T94_REG_WDAY] = bin2bcd(tm->tm_wday + 1); + buf[M41T94_REG_DAY] = bin2bcd(tm->tm_mday); + buf[M41T94_REG_MONTH] = bin2bcd(tm->tm_mon + 1); + + buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB; + if (tm->tm_year >= 100) + buf[M41T94_REG_HOURS] |= M41T94_BIT_CB; + buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100); + + return spi_write(spi, buf, 8); +} + +static int m41t94_read_time(struct device *dev, struct rtc_time *tm) +{ + struct spi_device *spi = to_spi_device(dev); + u8 buf[2]; + int ret, hour; + + /* clear halt update bit */ + ret = spi_w8r8(spi, M41T94_REG_HT); + if (ret < 0) + return ret; + if (ret & M41T94_BIT_HALT) { + buf[0] = 0x80 | M41T94_REG_HT; + buf[1] = ret & ~M41T94_BIT_HALT; + spi_write(spi, buf, 2); + } + + /* clear stop bit */ + ret = spi_w8r8(spi, M41T94_REG_SECONDS); + if (ret < 0) + return ret; + if (ret & M41T94_BIT_STOP) { + buf[0] = 0x80 | M41T94_REG_SECONDS; + buf[1] = ret & ~M41T94_BIT_STOP; + spi_write(spi, buf, 2); + } + + tm->tm_sec = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS)); + tm->tm_min = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES)); + hour = spi_w8r8(spi, M41T94_REG_HOURS); + tm->tm_hour = bcd2bin(hour & 0x3f); + tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1; + tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY)); + tm->tm_mon = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1; + tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR)); + if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB)) + tm->tm_year += 100; + + dev_dbg(dev, "%s secs=%d, mins=%d, " + "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", + "read", tm->tm_sec, tm->tm_min, + tm->tm_hour, tm->tm_mday, + tm->tm_mon, tm->tm_year, tm->tm_wday); + + return 0; +} + +static const struct rtc_class_ops m41t94_rtc_ops = { + .read_time = m41t94_read_time, + .set_time = m41t94_set_time, +}; + +static struct spi_driver m41t94_driver; + +static int m41t94_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + int res; + + spi->bits_per_word = 8; + spi_setup(spi); + + res = spi_w8r8(spi, M41T94_REG_SECONDS); + if (res < 0) { + dev_err(&spi->dev, "not found.\n"); + return res; + } + + rtc = devm_rtc_device_register(&spi->dev, m41t94_driver.driver.name, + &m41t94_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + spi_set_drvdata(spi, rtc); + + return 0; +} + +static struct spi_driver m41t94_driver = { + .driver = { + .name = "rtc-m41t94", + }, + .probe = m41t94_probe, +}; + +module_spi_driver(m41t94_driver); + +MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>"); +MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:rtc-m41t94"); |